OTTAWA - The government says pork is safe to eat despite a warning by the World Health Organization that the swine flu virus could survive in slaughtered pigs.

"Canadian pork is safe. There is no danger," Agriculture Minister Gerry Ritz insisted Wednesday after serving up pork sandwiches to MPs and government workers on Parliament Hill.

Earlier in the day, a WHO official said the pig strain of the H1N1 virus may withstand freezing and persist in the thawed meat and blood of infected animals.

The warning came as Canada's swine flu caseload jumped to 201, with 36 new mild cases reported. That included 13 in Ontario, eight in B.C., six in Quebec, five in Nova Scotia, and four in Alberta.

Also Wednesday, Canadian scientists became the first to genetically sequence the virus and confirm that the same strain is spreading through Canada and Mexico -- even though it has killed 42 Mexicans and been relatively mild here.

One possibility being considered is that the Mexican victims may have had underlying medical conditions that made them more susceptible to the bug.

Jorgen Schlundt, director of WHO's Department of Food Safety, Zoonoses and Foodborne Diseases, told Reuters it's possible for influenza viruses to survive the freezing process, and he cautioned against eating meat from sick and dead pigs infected with the swine flu.

But Dr. Brian Evans of the Canadian Food Inspection Agency said that's not an issue in Canada.

He said Canada has safeguards to keep diseased pigs from making it to market.

Those checks make it virtually impossible for infected pork to end up on store shelves, he said, since pigs are screened on farms for illnesses before they ever make it to the slaughterhouse.

Swine also undergo a clinical pre-assessment at slaughterhouses.

"The message that is coming out clearly from WHO today, which is standard operating practice in Canada, is the fact that you do not slaughter sick animals and you do not slaughter dead animals for human consumption," Evans said.

"This doesn't change anything in Canada. What the WHO is saying is what we do every day, every week, every month, every year as part of our food inspection system."

Dr. David Butler-Jones, Canada's chief public health officer, also said there's no cause for concern.

"There is no reason to stop eating pork," he said. "The inspection system in Canada does address all those issues."

Bacteria such as Listeria, salmonella and E. coli all pose a greater risk than swine flu in raw pork products, said Brian Ward, an infectious disease specialist at McGill University.

"Does this add any real risk to handling or preparation of pork products? No, I don't think so at all," Ward said.

"You'd really have to have a fairly extensive, linked series of improbable events that would all have to occur -- including, then, sticking your fingers in your eye without washing them."

The virus is killed by cooking meat at temperatures above 70 degrees Celsius.

There's no evidence that anyone has caught swine flu from eating pork. Still, 10 countries have banned Canadian pork products since the virus was found on an Alberta farm. China in particular banned pork from Alberta.

Canadian politicians and health officials have appealed to countries to lift the pork ban, which producers fear could do to their industry what the 2003 BSE outbreak did to the Canadian cattle industry when exports were shut down for more than a year.

Canadian pork exports were valued at $2.7 billion in 2008, including nearly $527 million worth of live swine exports.

Officials announced Wednesday that researchers at the National Microbiology Laboratory in Winnipeg had become the first to sequence Canadian and Mexican samples of the H1N1 virus.

And they have ruled out a mutation to explain why the Mexican cases have been much more severe than elsewhere.

Canada's cases have all been mild, with the exception of a young Alberta girl who came down with a severe case of the flu.

Frank Plummer of the National Microbiology Laboratory said scientists worked day and night to sequence the virus in less than a week.

"We're continuing our analysis, but essentially what it appears to suggest is that there's nothing at the genetic level that differentiates this virus that we've got from Mexico and those from Nova Scotia and Ontario that explains apparent differences in disease severity ...

"That's one of the big questions that everybody's been asking, so part of the answer is that it's likely not the virus itself that is explaining the differential and severity of disease between Mexico and the rest of North America."

Plummer said he hopes the breakthrough will help to identify origin of virus and reveal how it spreads and mutates.

Officials have said Canada's only severe case -- involving a girl in an Edmonton hospital -- had more to do with underlying conditions than it did with the virus itself.

The girl, who has not been identified, is getting better and is breathing on her own. It remained unclear how the girl, whose age was not released, became infected.

The federal Public Health Agency's website says the common flu sends, on average, about 20,000 Canadians to hospital each year. Between 4,000 and 8,000 can die of influenza and its complications annually, depending on the severity of the season.